Jeep Cherokee 2000 Service Manual - page 1099
CONDITION
POSSIBLE CAUSES
CORRECTION
ROUGH IDLE
(IRREGULARLY FIRING OR
ENGINE SHAKING)
1. If engine is cold, glow plug relay on
glow plug(s) defective.
1. Refer to troubleshooting for cylinder
head heater plugs (see Group 14, Fuel
system).
2. Engine mounts damaged or loose.
2. Repair or replace mounts.
3. High pressure fuel leaks.
3. Correct leaks in the high pressure
lines, fittings or delivery valves.
4. Air in the fuel system.
4. Bleed the fuel system and eliminate
the source of the air.
5. Sticking needle valve in an injector.
5. Check and replace the injector with
the sticking needle valve.
ENGINE RUNS ROUGH
1. Fuel injection lines leaking.
1. Correct leaks in the high pressure
lines, fittings, injectors sealing washers
or delivery valves.
2. Air in the fuel or the fuel supply is
inadequate.
2. Check the flow through the filter and
bleed the system. Locate and eliminate
the air source.
3. Contaminated fuel.
3. Verify by operating the engine with
clean fuel from a temporary supply
tank. Check for presence of gasoline.
Replace fuel/water separator filter.
4. Incorrect valve operation.
4. Check for a bent push rod and
adjust valves. Replace push rod, if
necessary.
5. Injection pump timing incorrect.
5. Check/time pump (refer to Group 14,
Fuel System).
6. Improperly operating injectors.
6. Replace inoperative injectors.
7. Defective injection pump (delivery
valve).
7. Repair or replace injection pump.
8. Camshaft out of time.
8. Check/correct gear train timing
alignment.
9. Damaged camshaft or tappets.
9. Inspect camshaft valve lift. Replace
camshaft and tappets.
10. Automatic timing advance not
operating.
10. Check injection pump. Check fuel
injector sensor at number 1 cylinder
injector.
ENGINE RPM WILL NOT
REACH RATED SPEED
1. Engine overload.
1. Verify high idle speed without load.
Investigate operation to be sure correct
gear is being used.
2. Improperly operating tachometer.
2. Verify engine speed with hand
tachometer, correct as required.
3. Inadequate fuel supply.
3. Check the fuel flow through the
system to locate the reason for
inadequate fuel supply, correct as
required.
4. Air/fuel controls leak.
4. Check and repair leak. Check AFC
tubing for obstruction.
XJ
ENGINE
9 - 5
DIAGNOSIS AND TESTING (Continued)